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But, to clarify: Is the sound coming from the camera (e.g., the lens) - meaning you hear it while recording? Or, is the sound captured on the recording? Is it associated with either the aperature or focus changing?

lifilmmaker

Thank you for your responses. Autofocus is off. A grinding noise can be heard in the camera during recording, when the video files are viewed after being transferred to a computer, as well as when holding the shutter button when shooting stills.

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paul13walnut5

The only other mechanical moving part is the sperture diaphragm, are you in autoexposure? Could the aperture be constantly changing? Try switching cam to manual exposure and see if the noise is still there.

Auto sound levels will vastly amplify the sound on the recording in a quiet environment, but in reality you should barely hear the iris operate.

I think we need to see / hear a clip.

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aerocanon

I believe you're referring to the AGC- Automatic Gain Control. You can install Magic Lantern on your T3i to (among other things) change the AGC to Manual, or you can buy a microphone which can be attached through the camera's 3.5mm microphone jack (consider the Rode VideoMic or the Rode VideoMic Pro). Besides for removing the annoying hiss, it will greatly improve your audio quality. You can also clean up the sound using software such as the Denoiser effect in Adobe Premiere Pro.

I believe you're referring to the AGC- Automatic Gain Control. You can install Magic Lantern on your T3i to (among other things) change the AGC to Manual, or you can buy a microphone which can be attached through the camera's 3.5mm microphone jack (consider the Rode VideoMic or the Rode VideoMic Pro). Besides for removing the annoying hiss, it will greatly improve your audio quality. You can also clean up the sound using software such as the Denoiser effect in Adobe Premiere Pro.

According to the ML user guide : " The 600D/T3i already has manual audio control, but right now it's not possible to change audio settings from Magic Lantern. You can only use audio meters during recording. "

Auto sound levels will vastly amplify the sound on the recording in a quiet environment, but in reality you should barely hear the iris operate.

Agreed that a clip will help. I suspect it is the aperature changing. As Paul states, that is the only mechanical action left. I disagree that you would barely hear the iris operate. I certainly have some lenses where this could be characterized as a grinding sound. My Zeiss 85mm is quite loud when changing aperature. Indeed, it makes a grinding sound. But, I never use auto exposure while shooting video (and don't recommend using auto exposure for video). If this is the grinding sound, then you'll easily get rid of it by using manual exposure.

And, yes. You can set the 600D/T3i's audio manually without Magic Lantern.

paul13walnut5

Sorry what are you saying? It reads as if you are saying that even if the camera is set to manual audio levels there is still automatic gain?

This is not my understanding. Do you know if the manual levels are a control of amplification or a measure of attenuation? I would hope they were a control of amplification, otherwise the noise will be there at all signal levels, which again, is not my experience.

aerocanon

It reads as if you are saying that even if the camera is set to manual audio levels there is still automatic gain?

Yes, the automatic gain is still there. Record a video with the T3i and listen- you'll hear plenty of noise, even if you set the recording level to manual.

Webopedia.com sums it up:"Abbreviated as AGC, automatic gain control is a circuit found on some electronic devices that automatically controls the gain of a signal. Using AGC means that weaker signals receive more gain and stronger signals receive less gain or none at all."Which results in noise caused by the AGC overcompensating.

aerocanon

I've been meaning to post this for a while but haven't because I don't go on this site very often.I posted earlier that attaching a microphone to the camera (T3i) will remove the AGC. This is not correct (ML -for T3i-cannot either change the AGC yet).But I did find this. I tried it and it works very well.

"If you're using an external recorder (such as a Rode Videomic Pro) make sure to send a hot signal (that will be something like a +db swith or a +20db switch) to your camera. Then, adjust the audio levels on your Canon DSLR almost all the way to the left, meaning turning them a few notches from being off. By sending a hot (high) signal from your external mic to a low gain level on your DSLR, you're avoiding the aforementioned [junky] camera preamps as much as possible. In my experience with the 60D and Rode VideoMic Pro, you can actually get FANTASTIC sound this way. On par with the Zoom H4N."

Has anyone ever experienced a grinding sound when shooting video with the T3i?

I have shot video with the 60D and the 5DII. On both cameras you can hear the IS. My solution is to turn off IS if using the internal mic, or the better solution, get an external mic. Just about any external mike will beat the in-camera mic. The key thing to look for is some form of isolation from the mic stand, or if hotshoe mounted, from the camera body. The lower picture shows details of a hotshoe mount... the green line points to the hotshoe mount, the red lines point to the elastics used to isolate the microphone from the mount, and the blue lines point to hair shed by Fluffy the cat. (cat hair is optional).